Hypotheses Being this a retrospective study, a formal hypothesis is not formulated. Background and Rationale Antiretroviral therapy has changed the natural history of HIV infection. However, antiretroviral therapy must be maintained for life. Its potential long-term adverse effects may interact synergistically with the ageing process, resulting in a higher incidence of comorbidities. The increasing number of non-antiretroviral drugs used to treat comorbidities may also place the patient at a higher risk of clinically meaningful interactions. Nowadays, efficacy is well demonstrated by all antiretroviral drugs compared with previous times. In fact a substantial number of HIV-infected patients from areas where antiretroviral therapy is widely available have achieved sustained suppression of plasma HIV replication. In contrast, the contributions of antiretroviral therapy to the development and progression of comorbidities and to the risk of potentially severe interactions have gained increasing importance as HIV-infected patients are getting older. More than half of HIV-infected patients aged ≥ 50 years have been reported to suffer from two or more concomitant comorbidities. In some of these patients, maintenance of antiretroviral therapy with combinations including NRTIs or PIs may be challenging. Data on ageing HIV patients under antiretroviral therapy are lacking.